We will need to evaluate whether it is constructive criticism, aimed at helping you succeed, or learn more. Or is it destructive criticism, targeting your personal beliefs and convictions. Attacking you personally is destructive, not constructive criticism. First, do whatever it takes to stay calm, and don’t lash back.
Decide whether th criticism is coming from a person with a reputation for truth or lies. Ask yourself, is this criticism meant to help or hurt me. Ecclesiastes 7:5 says “It is better to be criticized by a wise person than to be praised by a fool”.
Consider the reputation of the person who is criticizing you. Is he known to be negative and lash out at people, making cutting remarks? Or is he an honest man, with integrity and wisdom? Lastly, the only person you really need to have a clear conscience before is God. He alone knows your true heart and motive. Men judge from outward appearance, but God looks on the heart. Knowing this, you know you are able to shrug off unjustified criticism.